PHYTOCHROME CONTROL OF CHLOROPHYLL AND CAROTENOID BIOSYNTHESIS IN ETIOLATED WHEAT SEEDLINGS IN RELATION TO THE DARK PAUSE BETWEEN LIGHT IMPULSES

We studied regulatory action of the phytochrome system on the kinetics of chlorophyll and carotenoid accumulation in etiolated wheat seedlings (Triticum aestivum L.) greening under white light. The phytochrome system was excited by an impulse of red light and after a certain dark pause was returned to the starting state by an impulse of far red light. The value of activation of the biological effect was found to grow linearly with increase of the dark pause. The obtained result agrees with a model proposed previously by the author to describe phytochrome regulation of biological processes occurring a significant time after relaxation of the phytochrome system.